Update: six days I've hibernated and 'messages' was type unknown. After shutdown and reboot 'messages' were type textfile again and of course no error message anymore in log viewer GUI.
Now log viewer prompts message about 'btmp' I'm not allowed to read this document. I've checked permissions and they're 660 (root-utmp-others), fine with me. (attached screenshot)
Update: six days I've hibernated and 'messages' was type unknown. After shutdown and reboot 'messages' were type textfile again and of course no error message anymore in log viewer GUI.
Now log viewer prompts message about 'btmp' I'm not allowed to read this document. I've checked permissions and they're 660 (root-utmp-others), fine with me. (attached screenshot)